1. Field of the Invention
The present invention relates to a laser processing method. More particularly, the invention relates to a method of manufacture that uses such laser processing, for example, to manufacture an ink jet recording head for enabling ink droplets to fly and adhere to a recording medium, and also, relates to an ink jet recording head manufactured by such method of manufacture.
2. Related Background Art
Conventionally, there has been known the laser processing method that uses ultraviolet laser in order to precisely process a structural object that requires minute structures formed in high precision.
As an example of such precise processing, there is such one as processing ink flow paths or ink discharge ports of an ink jet head.
In the specification of Japanese Patent Application Laid-Open No. 2-121842 or 2-121845, is disclosed the high precision processing of ink flow paths or ink discharge ports using excimer layer, the typical ultraviolet laser.
In other words, the excimer laser can oscillate ultraviolet rays of short pulses (15 to 35 ns) by the discharge excitation of a mixed gas of rare gas and halogen. The oscillation energy thereof is 100 mJ/pulse, and pulse repetition frequency is 10 to 500 Hz. Then, when the highly bright ultraviolet rays, such as the excimer layer, are radiated on the surface of resin polymer, the ablative photodecompotion (APD) process occurs to decompose such portion to be scattered instantaneously with plasma emission and impact noises, thus making it possible to perform the so-called laser ablation process of polymer resin.
With the YAG laser which has been generally in use as a laser processing, edge faces tend to become rough, although drilling is possible. Also, the CO2 laser, which is infrared, has a drawback that crater is made on the circumference of each hole. Here, the laser processing of the kind is the so-called laser heat process, which is executed by transforming light energy into thermal energy. As a result, the processed shape is liable to be collapsed to make precise processing difficult. In contrast, the ablation process that uses excimer laser performs sublimation etching by means of the photochemical reaction that cuts the covalent binding of carbon atoms. Therefore, processed shape is not easily collapsed, hence making it possible to execute an extremely precise processing.
Here, the ablation process means a method for performing sublimation process by use of laser without conditioning any liquid phase.
Particularly, in the field of ink jet technologies and techniques, the practical use of laser ablation process has remarkably developed in recent years as fresh in the memory of those skilled in the art.
Further, while practicing the laser process using excimer laser, the following has been found: in other words, the oscillating pulses of radiated laser is approximately several tens of nano seconds per pulse for the excimer layer, that is, the aforesaid ultraviolet laser, while the ultraviolet harmonic oscillation of YAG laser is approximately 100 pico seconds to several nano seconds. However, the light energy of the laser beams radiated on a work piece is not necessarily used all for cutting the covalent binding of atoms.
Then, because of the existence of light energy which is not used for cutting the covalent binding of atoms, the laser processed portion of a work piece is scattered before being completely decomposed. Thus, a by-product is created on the circumference of the processed portion.
Also, a part of light energy which is not used for cutting the covalent binding of atoms is converted into thermal energy.
The energy density of excimer laser reaches only a 100-megawatt level at the maximum in terms of oscillating pulses. Therefore, it becomes difficult to process. metal, ceramics, and minerals (such as silicon) having high ratio of heat transfer, and quartz and glass having low light absorptance. Mainly, organic resin materials can be processed by use of sublimating ablation.
These have been unavoidable phenomena that may take place when using excimer laser. Therefore, various processing techniques have been proposed so that these phenomena do not produce unfavorable influences on the recording heads to be used actually.
For example, if an ink jet recording head is assembled with the aforesaid by-product yet to be eliminated, it may cause clogging of discharge ports. Here, a processing step should be provided additionally in order to remove the by-product.
Also, with a part of light energy being converted into thermal energy, a work piece may be caused to expand while it is processed or there is a fear that the work piece tends to be partly fused. Therefore, a material having a high glass transition point or a material having a lower processing pitch should be used.
Nevertheless, as described above, no fundamental solution has been given to any one of these techniques. The actuality is, therefore, that various restrictions should be imposed upon laser processing.
On the other hand, for the ink jet recording head described above, it has been required to provide highly precise images in recent years. For that matter, whereas the arrangement density of 300 to 400 dpi should be good enough conventionally, it is now demanded to provide that of 600 dpi or as high as 1,200 dpi in recent years.
Under the circumstances, the arrangement intervals of discharge ports and recording liquid flow paths should be processed in higher precision at extremely small intervals of 50 xcexcm or less or in the extremely small diameter of 20 xcexcm or less.
However, since the phenomena observable for the excimer laser processing as described above become more conspicuous as the process intervals or process diameters become smaller, there has begun a limit in using it for manufacturing a head of such a highly precise type as described earlier.
In this respect, the inventors hereof have recognized that the aforesaid phenomena are brought about by the laser ablation processing using the ultraviolet laser which is typically represented by the excimer laser, and assiduously made studies from the new point of view completely free from the conventional art. As a result, the fundamental solution has been found to eliminate these phenomena, and a revelational laser ablation processing technique has been found, which can deal with the microprocessing that makes further progress from now on, and which contributes to enhancing the versatility of such technique.
The present invention is designed with a view to solving the technical problems discussed above. It is an object of the invention to provide a laser processing method capable of performing a highly precise processing without creating by-product, while preventing fundamentally the thermal energy converted during the operation of laser processing from being accumulated on a work piece, such as resin, without fusing the work piece or causing thermal expansion, and also to provide a method for manufacturing an ink jet recording head using such laser processing method, as well as an ink jet recording head manufactured by such method of manufacture.
It is another object of the invention to provide a laser processing method capable of performing processing with simple and easy steps when processing a precise structural member formed by materials of plural kinds to be provided for a work pieces, and also, to provide a method for manufacturing an ink jet recording head using such laser processing method, as well as an ink jet recording head manufactured by such method of manufacture.
Also, it is still another object of the invention to provide a laser processing method which makes it possible to simplify the alignment step, and also, implement to increase the positional precision of the inner structural member or the like, while reducing the costs of manufacture, among some others, and also, to provide a method for manufacturing an ink jet recording head using such laser processing method, as well as an ink jet recording head manufactured by such method of manufacture.
It is a further object of the invention to provide a laser processing method capable of structuring a work piece to absorb the radiated energy of laser in order to attempt the enhancement of processing efficiency, and also, to provide a method for manufacturing an ink jet recording head using such laser processing method, as well as an ink jet recording head manufactured by such method of manufacture.
In order to achieve these objectives, the present invention provides the laser processing method structured in the following paragraphs from (1) to (48). It also provides a method for manufacturing an ink jet recording head using such laser processing method, and an ink jet recording head manufactured by such method of manufacture.
(1) A laser processing method for performing laser ablation process on a work piece by radiating laser beam on the work piece comprises the step of-forming simultaneously a plurality of process shapes arranged at a predetermined interval by use of laser beam of plural pulses having extremely large spatial and temporal energy density radiated from a laser oscillator as the laser beam oscillating at the pulse radiation time of one picosecond or less.
(2) For the laser processing method described in the above paragraph (1), the material used is resin, Si, or Si compound material.
(3) A laser processing method comprises the steps of converging and irradiating with predetermined energy density the laser beam of plural pulses having large spatial and temporal energy density radiated from a laser oscillator oscillating at the pulse radiation time of one picosecond or less onto a work piece formed by different materials of two kinds or more; and performing sublimating processing of the different materials of two kinds or more in one and the same step almost simultaneously.
(4) For the laser processing method described in the above paragraph (3), the work piece used is formed by different materials of two kinds or more in a bonded state, and then, the work piece is processed by sublimation almost simultaneously in one and the same step without creating warping.
(5) For the laser processing method described in the above paragraph (3), the different materials of two kinds or more are formed by an arbitrary combination of organic resin material, metallic material, inorganic compound material, glass material, mineral material, and the like.
(6) A laser processing method for performing laser ablation processing by irradiating laser beam to a work piece comprises the steps of using laser beam of plural pulses having extremely large spatial and temporal energy density radiated from a laser oscillator as the laser bemas oscillating at the pulse radiation time of one picosecond or less to converge beam with more than predetermined energy density inside a transparent work piece with respect to the light wavelength of the laser beam; and processing the work piece by sublimation.
(7) A laser processing method for performing laser ablation processing by irradiating laser beam to a work piece comprises the steps of using laser beam of plural pulses having extremely large spatial and temporal energy density radiated from a laser oscillator as the laser beam oscillating at the pulse radiation time of one picosecond or less to be passed through an almost transparent material (A) with respect to the light wavelength of the laser beam, having lower light absorptance, and radiating the laser beam on a material (B) positioned inside the work piece, having higher light absorptance with respect to the light wavelength of the laser beam than that of the material (A); and processing the material (B).
(8) For the laser processing method described in the above paragraph (6), when a structural member is processed by sublimation inside a work piece, a discharge port is formed in advance to discharge to the outside the by-product created by sublimation and evaporation caused by the processing the structural member is processed.
(9) For the laser processing method described in the above paragraph (8), when the structural member is processed, this member is processed in a position close to the discharge port.
(10) For the laser processing method described in either one of the above paragraphs (1) to (9), when processing is performed, the work piece is colored by mixing therein a dye for absorbing wavelength in a domain corresponding to the oscillating wavelength of the laser beam, and processed.
(11) The wavelength of the laser beam is within a domain of 350 to 1000 nm for the laser processing method described in either one of the above paragraphs (1) to (10).
(12) For a laser processing method described in either one of the above paragraphs (1) to (11), the pulse radiation time of the laser beam is set at 500 femtoseconds or less.
(13) For a laser processing method described in either one of the above paragraphs (1) to (11), the laser oscillator is the one which is provided with a spatial compression device for propagating beam.
(14) For a laser processing method described in the above paragraph (13), the spatial compression device for propagating beam comprises chirping pulse generating means and longitudinal mode synchronous means utilizing light wavelength dispersion characteristics.
(15) For the laser processing method described in the above paragraph (13), the spatial compression device for propagating beam is structured using charping pulse generating means and the longitudinal mode synchronous method utilizing the light wavelength dispersion characteristic of diffraction phase grating.
(16) A method for manufacturing an ink jet recording head having a member for forming at least a part of ink passage for ink to flow to be processed by laser beam, provided with an ink discharge port for discharging ink droplet adhering to a recording medium; a liquid chamber for retaining ink to be supplied to the discharge port; an ink flow path communicated with the discharge port and the liquid chamber; an energy generating element arranged for a part of the ink flow path for generating energy for discharging ink; and an ink supply port for supplying ink from the outside into the liquid chamber, comprises the step of forming recessed portion becoming a part of the ink passage or through hole by use of laser beam of plural pulses having extremely large spatial and temporal energy density radiated from a laser oscillator as the laser beam oscillating at the pulse radiation time of one picosecond or less.
(17) For the method for manufacturing an ink jet recording head described in the above paragraph (16), the recessed portion or through holes becoming a part of the ink passage are formed in plural numbers at a predetermined pitch simultaneously by radiating laser beam through a mask having plural openings formed at a predetermined space.
(18) For the method for manufacturing an ink jet recording head described in the above paragraph (16) or (17), the member forming at least a part of the ink passage is formed by resin.
(19) For the method for manufacturing an ink jet recording head described in the above paragraph (16) or (17), the member forming at least a part of the ink passage is formed by Si or Si compound material.
(20) For the method for manufacturing an ink jet recording head described in either one of the above paragraphs (17) to (19), the recessed portion is a groove becoming the ink flow path.
(21) For the method for manufacturing an ink jet recording head described in either one of the above paragraphs (17) to (19), the through hole becomes the discharge port.
(22) A method for manufacturing an ink jet recording head having a member for forming at least a part of ink passage for ink to flow to be formed by different materials of two kinds or more, the member formed by different materials of two kinds or more being processed by laser beam, provided with an ink discharge port for discharging ink droplets adhering to a recording medium; a liquid chamber for retaining ink to be supplied to the discharge port; an ink flow path communicated with the discharge port and the liquid chamber; an energy generating element arranged for a part of the ink flow path for generating energy for discharging ink; and an ink supply port for supplying ink from the outside into the liquid chamber, comprises the step of processing the member formed by different materials of two kinds or more by sublimation almost simultaneously in one and the same step by use of laser beam of plural pulses having extremely large spatial and temporal energy density radiated from a laser oscillator as the laser beam oscillating at the pulse radiation time of one picosecond or less.
(23) For the method for manufacturing an ink jet recording head described in the above paragraph (22), the member formed by different materials of two kinds or more is structured in a bonded state constituting at least a part of ink passage of an ink jet recording head, and processed by sublimation almost simultaneously in one and the same step without creating warping.
(24) For the method for manufacturing an ink jet recording head described in the above paragraph (22) or (23), the different materials of two kinds or more are an arbitrary combination of organic resin material, metallic material, inorganic compound material, glass material, mineral material and the like.
(25) A method for manufacturing an ink jet recording head having a member for forming at least a part of ink passage for ink to flow to be formed in a transparent ink flow path formation member and processed by laser beam, provided with an ink discharge port for discharging ink droplets adhering to a recording medium; a liquid chamber for retaining ink to be supplied to the discharge port; an ink flow path communicated with the discharge port and the liquid chamber; an energy generating element arranged for a part of the ink flow path for generating energy for discharging ink; and an ink supply port for supplying ink from the outside into the liquid chamber, comprises the steps of using laser beam of plural pulses having extremely large spatial and temporal energy density radiated from a laser oscillator as the laser beam oscillating at the pulse radiation time of one picosecond or less to converge beam with more than predetermined energy density inside the transparent ink flow path formation member with respect to the light wavelength of the laser beam; and processing an ink flow path and others by sublimation.
(26) A method for manufacturing an ink jet recording head having a member for forming at least a part of ink passage for ink to flow to be formed by a substantially transparent material (A) having low light absorptance of laser beam, and a material (B) having higher light absorptance than that of the material (A) and positioned inside a work piece, and processed by the laser processing method, provided with an ink discharge port for discharging ink droplets adhering to a recording medium; a liquid chamber for retaining ink to be supplied to the discharge ports; an ink flow path communicated with the discharge port and the liquid chamber; an energy generating element arranged for a part of the ink flow path for generating energy for discharging ink; and an ink supply port for supplying ink from the outside into the liquid chamber, comprises the steps of using laser beam of plural pulses having extremely large spatial and temporal energy density radiated from a laser oscillator as the laser beam oscillating at the pulse radiation time of one picosecond or less to pass beam the material (A) having low light absorptance of the laser beam, and radiate beam on the material (B) having higher light absorptance than that of the material (A) and positioned inside the work piece; and processing the material (B) by sublimation.
(27) For the method for manufacturing an ink jet recording head described in the above paragraph (25) or (26), when the ink flow path and others are processed, a discharge port is formed in advance to discharge to the outside the by-product created by the sublimation and vaporization of the processing, and then, the ink flow path and others are processed.
(28) For the method for manufacturing an ink jet recording head described in the above paragraph (27), when the ink flow path and others are processed, the ink flow path and other are processed in a position close to the discharge port.
(29) For the method for manufacturing an ink jet recording head described in either one of the above paragraphs (16) to (28), the work piece is colored by mixing therein a dye for absorbing wavelength in a domain corresponding to the oscillating wavelength of the laser beam, and processed.
(30) For the method for manufacturing an ink jet recording head described in either one of the above paragraphs (16) to (29), the wavelength of the laser beam is within a domain of 350 to 1000 nm.
(31) For the method for manufacturing an ink jet recording head described in either one of the above paragraphs (16) to (30), the pulse radiation time of the laser beam is 500 femtoseconds or less.
(32) For the method for manufacturing an ink jet recording head described in either one of the above paragraphs (16) to (31), the laser oscillator is a laser oscillator provided with a spatial compression device for propagating beam.
(33) For the method for manufacturing an ink jet recording head described in the above paragraph (32), the spatial compression device for propagating beam comprises chirping pulse generating means and longitudinal mode synchronous means utilizing light wavelength dispersion characteristics.
(34) For the method for manufacturing an ink jet recording head described in the above paragraph (32), the spatial compression device for propagating beam is structured using charping pulse generating means and the longitudinal mode synchronous method utilizing the light wavelength dispersion characteristic of diffraction phase grating.
(35) An ink jet recording apparatus having a member for forming at least a part of ink passage to be processed by laser beam, provided with an ink discharge port for discharging ink droplets adhering to a recording medium; a liquid chamber for retaining ink to be supplied to the discharge port; an ink flow path communicated with the discharge port and the liquid chamber; an energy generating element arranged for a part of the ink flow path for generating energy for discharging ink; and an ink supply port for supplying ink from the outside into the liquid chamber, comprises a recessed portion or through hole becoming a part of the ink passage, to be formed by use of laser beam of plural pulses having extremely large spatial and temporal energy density radiated from a laser oscillator as the laser beam oscillating at the pulse radiation time of one picosecond or less.
(36) For the ink jet recording head described in the above paragraph (35), the recessed portion or through hole becoming a part of the ink passage are formed in plural numbers at a predetermined pitches simultaneously by radiating laser beam through a mask having plural openings formed at a predetermined pitches.
(37) For the ink jet recording head described in the above paragraph (35) or (36), the member forming at least a part of the ink passage is formed by resin.
(38) For the ink jet recording head described in either one of the above paragraphs (35) to (37), the member forming at least a part of the ink passage is formed by Si or Si compound material.
(39) For the ink jet recording head described in either one of the above paragraphs (36) to (38), the recessed portion is a groove becoming the ink flow path.
(40) For the ink jet recording head described in either one of the above paragraphs (36) to (39), the through hole becomes the discharge port.
(41) An ink jet recording head having a member for forming at least a part of ink passage to be formed by different materials of two kinds or more, the member formed by different materials of two kinds or more being processed by laser beam, provided with an ink discharge port for discharging ink droplets adhering to a recording medium; a liquid chamber for retaining ink to be supplied to the discharge port; an ink flow path communicated with the discharge port and the liquid chamber; an energy generating element arranged for a part of the ink flow path for generating energy for discharging ink; and an ink supply port for supplying ink from the outside into the liquid chamber, comprises the member having different materials of two kinds or more processed by sublimation almost simultaneously in one and the same step by use of laser beam of plural pulses having extremely large spatial and temporal energy density radiated from a laser oscillator as the laser beam oscillating at the pulse radiation time of one picosecond or less.
(42) For the ink jet recording head described in the above paragraph (41), the member formed by different materials of two kinds or more is structured in a bonded state constituting at least a part of ink passage of an ink jet recording head, and processed by sublimation almost simultaneously in one and the same step without creating warping.
(43) For the ink jet recording head described in the above paragraph (41) or (42), the different materials of two kinds or more are an arbitrary combination of organic resin material, metallic material, inorganic compound material, glass material, mineral material and the like.
(44) An ink jet recording head having a member for forming at least a part of ink passage to be formed in a transparent ink flow path formation member and processed by laser beam, provided with an ink discharge port for discharging ink droplets adhering to a recording medium; a liquid chamber for retaining ink to be supplied to the discharge port; ink flow path communicated with the discharge port and the liquid chamber; an energy generating element arranged for a part of the ink flow path for generating energy for discharging ink; and an ink supply port for supplying ink from the outside into the liquid chamber, comprises the member processed by sublimation by use of laser beam of plural pulses having extremely large spatial and temporal energy density radiated from a laser oscillator as the laser beam oscillating at the pulse radiation time of one picosecond or less to be converged with more than predetermined energy density inside the transparent ink flow path formation member with respect to the light wavelength of the laser beam.
(45) An ink jet recording head having a member for forming at least a part of ink passages to be formed by a substantially transparent material (A) having low light absorptance of laser beam, and a material (B) having higher light absorptance than that of the material (A) and positioned inside a work piece, and processed by the laser processing method, provided with an ink discharge port for discharging ink droplets adhering to a recording medium; a liquid chamber for retaining ink to be supplied to the discharge port; an ink flow path communicated with the discharge port and the liquid chamber; an energy generating element arranged for a part of the ink flow path for generating energy for discharging ink; and an ink supply port for supplying ink from the outside into the liquid chamber, comprises the member processed by sublimation by use of laser beam of plural pulses having extremely large spatial and temporal energy density radiated from a laser oscillator as the laser beam oscillating at the pulse radiation time of one picosecond or less to be passed through the material (A) having low light absorptance of the laser beam, and radiated on the material (B) having higher light absorptance than that of the material (A) and positioned inside the work piece.
(46) For the ink jet recording head described in the above paragraph (44) or (45), when the ink flow path and others are processed, a discharge port is formed in advance to discharge to the outside the by-product created by the sublimation and vaporization of the processing, and then, the ink flow path and others are processed.
(47) For the ink jet recording head described in the above paragraph (46), when the ink flow path and others are processed, the processing thereof is performed in a position close to the discharge port.
(48) The ink jet recording head described in either one of the above paragraphs (35) to (47) further comprises a member colored by mixing therein a dye for absorbing wavelength in a domain corresponding to the oscillating wavelength of the laser beam, and processed.